shale

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shale,

sedimentary rockrock,
aggregation of solid matter composed of one or more of the minerals forming the earth's crust. The scientific study of rocks is called petrology. Rocks are commonly divided, according to their origin, into three major classes—igneous, sedimentary, and metamorphic.
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 formed by the consolidation of mud or clay, having the property of splitting into thin layers parallel to its bedding planes. Shale tends to be fissile, i.e., it tends to split along planar surfaces between the layers of stratified rock. Shales comprise an estimated 55% of all sedimentary rocks. The composition of shale varies widely. Shales with very high silica content may have been formed when large quantities of diatomsdiatom
, unicellular organism of the kingdom Protista, characterized by a silica shell of often intricate and beautiful sculpturing. Most diatoms exist singly, although some join to form colonies.
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 and volcanic ash were present in the original sediment. Large numbers of fossilsfossil,
remains or imprints of plants or animals preserved from prehistoric times by the operation of natural conditions. Fossils are found in sedimentary rock, asphalt deposits, and coal and sometimes in amber and certain other materials.
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 in shales may give them a high calcium content; such shales may grade into limestoneslimestone,
sedimentary rock wholly or in large part composed of calcium carbonate. It is ordinarily white but may be colored by impurities, iron oxide making it brown, yellow, or red and carbon making it blue, black, or gray. The texture varies from coarse to fine.
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. Shales that contain a large percentage of aluminaalumina
or aluminum oxide,
Al2O3, chemical compound with m.p. about 2,000°C; and sp. gr. about 4.0. It is insoluble in water and organic liquids and very slightly soluble in strong acids and alkalies. Alumina occurs in two crystalline forms.
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 are used as a source of that mineral in the manufacture of cementcement,
binding material used in construction and engineering, often called hydraulic cement, typically made by heating a mixture of limestone and clay until it almost fuses and then grinding it to a fine powder.
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, and those that contain natural gas and petroleum have become a significant energy resource in the 21st cent. due to the use of hydraulic fracturing techniques in drilling. Shales containing abundant carbonaceous matter grade into bituminous coalcoal,
fuel substance of plant origin, largely or almost entirely composed of carbon with varying amounts of mineral matter. Types

There is a complete series of carbonaceous fuels, which differ from each other in the relative amounts of moisture, volatile matter,
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.

shale

[shāl]
(petrology)
A fine-grained laminated or fissile sedimentary rock made up of silt- or clay-size particles; generally consists of about one-third quartz, one-third clay materials, and one-third miscellaneous minerals, including carbonates, iron oxides, feldspars, and organic matter.

shale

Argillaceous sedimentary rock derived from clays or silts; typically thinly laminated and weak along planes; may be undesirable as a concrete aggregate.

shale

a dark fine-grained laminated sedimentary rock formed by compression of successive layers of clay-rich sediment
References in periodicals archive ?
Oil shales that contain many metal trace elements have drawn increasing attention in recent times.
In August, a senior energy official announced that Iran is cooperating with renowned German energy firms in its shale gas and oil projects.
It was stressed that the key trends of the global shale gas industry in 2013 2014 were the declined rates of gas production from the US shale deposits and the lack of any progress in developing shale gas resources beyond North America.
We also explore the factors driving growth in the US oil shales industry such as the increase in oil prices, energy security, and economic benefits, amongst others.
In addition to gas shales, there is also potential for oil shales in Oman, he explains.
This leaves a weaker proximity to brittle rock layers, such as limestones or dolomites, which can be fractured, propped and serve as drainage pathways for the gas entrapped in the shales.
Keywords: oil shale demineralization, bioleaching, shale oil yield, Bacillus mucilaginosus, Thiobacillus ferrooxidans.
For the first time, the kingdom is giving serious consideration to exploiting its unconventional energy reserves, following the revelation by Saudi Aramco chief executive officer, Khalid Al Falih, in September 2010 that the country possesses "hundreds of trillions of cubic feet of shale gas".
However, the thermal conductivities of Jimsar and Green River oil shales are almost similar.
Characteristics and genetic types of continental oil shales in China.